The invention is directed to a method for fastening electronic components to a substrate with a connecting layer sintering from a metal powder, and also relates to a film for implementation of the method and to a method for the manufacture of such a film.
Arrangements wherein components parts are secured to substrates and methods for manufacture are known from various publications. A connecting layer between the component part and substrate needed for fastening can be manufactured in various ways, but should always meet the same demands with respect to low electrical resistance, high thermal conductivity, and high adhesion.
German Published Application No. 34 14 065, incorporated herein by reference, discloses that the connecting layer can be exclusively manufactured from metal powder solidified by dry sintering. On the one hand, the contacting layer of the component, and on the other hand, the contact surface of the substrate, are also sintered. A bonding agent such as glass or glue is omitted. The manufacturing method of this arrangement provides that a paste formed of metal powder and of a solvent is applied in layer-like fashion to the contacting layer of the component and/or to the contact surface of the substrate. The component is placed onto the substrate or the paste, the solvent is completely driven out, and the overall arrangement is heated to sintering temperature for the formation of the connecting layer. It is thus fundamentally possible to degasify the paste in a vacuum before the component part is put in place, to subsequently pre-dry it, and to subsequently drive the solvent completely out after the component part is put in place. The sintering process is then subsequently carried out. The sintering temperature lie between 380.degree. and 420.degree. C. The mechanical pressure is set to a value between 80 and 90 N/cm.sup.2.
German patent application, Ser. No. P 36 13 572.0, corresponding to U.S. Ser. No. 029,819 filed Mar. 25, 1987, now U.S. Pat. No. 4,810,672 incorporated herein by reference, discloses that a paste applied to the substrate and/or to the component before the component is put in place must be completely dried. The procedure is especially important given large-area components since a drying of the paste after the component has already been put in place leads to errors in the connecting layer. Disadvantages of this procedure are compensated by an extremely high mechanical pressure of at least 900 N/cm.sup.2 during the sintering process.